A dependent clause may serve as a noun. This noun clause may function as the subject or as any other noun in the sentence. Common first words of noun clauses are the pronouns: that, who, whom, what, and whoever.

Example:

Consider the following: "Whoever is selected as the quarterback must be able to lead the team." The underlined noun clause serves as the subject of the sentence. Notice that noun clauses are not marked off from the rest of the sentence by commas.